This invention relates generally to microbiological systems, and more particularly to specific methods and apparatus for use in a microbiological laboratory for miniaturization and automation of microbiological procedures.
Microbiology laboratories are generally equipped with numerous apparatus for providing serial dilutions of the microbiological sample, distribution equipment for applying the diluted samples to appropriate growth medium, incubation equipment where the micro-organisms are permitted to grow on the medium, and various testing equipment to analyze the results of the growth. The various apparatus must generally be maintained in a sterile atmosphere to prevent cross contamination from other microbiological organisms. Although various automated equipment has been suggested for use in the microbiological laboratory, these equipment have been of extremely large scale and have been of limited value since many of them can perform only one small aspect of the microbiological laboratory. Much of the laboratory still relies upon individualized manual effort. As a result, the size of the microbiological laboratory is generally extensive, the number of personnel is quite high, and the cost of any anaylsis is excessive.
One of the reasons for the difficulty in miniaturizing and automating the microbiological laboratory involves the problem of providing appropriate dilutions of the microbiological sample. Generally, some form of serial dilution is required, typically a log distribution, in applying the sample onto a growth medium. This is generally achieved by the dilution of a sample and application of the diluted sample by means of a loop onto a growth medium utilizing a serpentine streaking onto a Petri dish. The automated equipment heretofore provided tried to mechanically duplicate the serpentine streaking onto the Petri dish. As a result, the size of the equipment needed was quite large and the speed was relatively slow.
A further problem with miniaturizing and automating the microbiological laboratory concerned the distribution of diluted samples into receiving wells. Although small receiving wells could be achieved on a single array, the problem faced was how to apply the exact amount of diluted sample to each receiving well. Various prior art apparatus utilized an injection principal which filled the receiving wells in a stepwise manner. This process was slow and again required large size equipment.
Numerous other problems unique to the microbiological laboratory have prevented the automation and miniaturization of the equipment needed. For example, the need for maintaining the equipment in a sterile atmosphere provided specific restraint which prevented direct application of automatic equipment from other laboratories into the microbiological field. Additionally, the necessity for providing the serial dilution of the sample provides an increased time and space problem not necessarily required in other scientific laboratory work. Accordingly, while other fields of medicine, such as biochemistry, have advanced to the state of automation and miniaturization, the microbiological laboratory has yet to achieve the advanced state of progress which has been available in related fields of medicine.